DELTA®-TERRAXX drainage system


The high-performance protection and drainage system DELTA®-TERRAXX constitutes the all-round solution for horizontal and vertical applications on compression-resistant surfaces.  

This dimpled sheet has a life of 100 years as shown in endurance tests, is certified under EN 13252, and conforms to the requirements of DIN 4095, DIN 18533, and DIN 18531.

DELTA®-TERRAXX für senkrechte Anwendungenzoom

Vertical waterproofing

DELTA®-TERRAXX für Dachbegrünungenzoom

Planted roof

DELTA®-TERRAXX unter Kies-, Platten- und Holzbelägenzoom

Gravel, flag, or wood pavement


Driveable surfaces


DELTA®-TERRAXX for horizontal applications

DELTA®-TERRAXX has been optimised for various applications in horizontal drainage. Laid on top of the waterproofing, this 2-ply water drainage sheet constitutes an all-round solution conforming to DIN 18531 and DIN 4095. It serves to protect e.g. paved underground parking decks, terraces, and planted roofs from impounded water and is installed under the wearing course of parking decks.

The composite of a dimpled sheet and a fused-on geotextile forms a highly effective drainage layer. Facing up, the geotextile acts as a filtration layer for the hollow spaces contained in the dimpled sheet underneath. Between DELTA®-TERRAXX and the waterproofing sheet, a conventional 300-g spunbond should be inserted.    

No higher than 9mm, the dimpled sheet ensures a low add-on height, although its drainage capacity is markedly greater than that of a gravel or chip bed. Its high water drainage capacity ensures that water drains away unhindered, besides providing safe and effective protection from impounded water and the problems related to it, such as obstruction by growing moss or dying vegetation.

In terms of weight, too, DELTA®-TERRAXX is clearly superior to drainage layers of gravel or chips. The protection and drainage sheet is equally suitable for extensive and intensive planting. DELTA®-TERRAXX is also capable of dealing with extreme volumes of water. Thanks to their self-sealing overlap edges, the sheets may be interconnected safely so they cannot be blown up by wind.

DELTA®-TERRAXX horizontal applicationzoom

DELTA®-TERRAXX may be used with walkable, driveable, and planted roof surfaces as well as with wooden terrace floorings, such as Bangkirai.

For planted roofs: 
In intensely planted roofs with thick substrate layers, this 2-ply sheet acts as a protection, filtration, and seepage layer, ensuring that no impounded water can gather. 

For walkable and driveable surfaces: 
In this case, DELTA®-TERRAXX forms a heavy-duty protection and drainage layer, thus protecting the pavement from frost damage. 

For terraces paved with flagstones or wood: 
DELTA®-TERRAXX performs the function of a drainage layer and ensures that water drains out of the structure quickly, thus preventing damage to the pavement. 

For gravelled roofs: 
Installed under a gravel bed, DELTA®-TERRAXX offers optimum protection for the waterproofing below.

DELTA®-TERRAXX horizontal application
DELTA®-TERRAXX horizontal application
DELTA®-TERRAXX horizontal application

Impact sound abatement with DELTA®-TERRAXX: up to 32dB

The transmission of body-borne sound into adjacent or underlying rooms initiated by e.g. people walking or objects dropping is called impact sound transmission. Excited by body-borne sound, the floor/ceiling construction transmits the impact noise in the form of airborne noise. An impact noise reduction by 10dB is perceived by the human ear as a 50-% reduction.

DELTA®-TERRAXX protection and drainage sheets are tested for impact sound transmission. They not only protect the waterproofing, withstand very tough conditions, and prevent damage from impounded water; they also provide outstanding noise abatement in various applications under gravel, cobblestone, flagstone, and wood pavements.

In conformance with DIN ISO 10140, the Rhein-Main University of Wiesbaden conducted tests under as-installed conditions to determine the extent to which impact noise is reduced by installing DELTA®-TERRAXX in combination with various waterproofing, pavement, and chip varieties. For the tests, the sound-absorbing DELTA®-TERRAXX protection and drainage sheet was installed between the waterproofing and the pavement or chip bed. The result: impact noise was reduced by up to 32dB.

DELTA®-TERRAXX Trittschallverbesserung zoom

Application of DELTA®-TERRAXX 

DELTA®-TERRAXX may be laid quickly, safely, and cost-efficiently straight off the roll. Simply roll out the sheet on the surface, always with the permanent-filtration geotextile facing upwards. Installing the sheet around details is very easy as well. In overlap zones, one edge of the sheet is smooth and equipped with a self-sealing strip. Coming in rolls with a fused-on filtration cloth, the sheet may be laid efficiently on a waterproofed surface. It is laid loosely on a waterproofed surface. A layer of sand or chips may be applied directly on top of it, followed by a pavement of cobblestones, wood, or flagstones. Installed under cobblestones, flagstones, or wooden terrace pavements, this continuous drainage layer ensures that any precipitation water that may have seeped into the superstructure will drain off without delay. Clogging up by moss or soot, silting, and frost heaves are avoided.   

DELTA®-TERRAXX for vertical waterproofing

Installed in front of the cellar wall waterproofing, DELTA®-TERRAXX offers maximum safety by forming a second water-impermeable envelope against impounded, artesian, and seepage water. Pointing towards the soil, the dimples form a continuous drainage layer that protects the perimeter insulation or the DELTA®-THENE waterproofing sheet not only from moisture but also from soil or root movements. The sheet exceeds the requirements of DIN 4095. 

The fused-on geotextile keeps the dimple structure from silting up. Consequently, DELTA®-TERRAXX permanently offers the outstanding drainage capacity of 3.1L(ms).  

With its width of 2.40m, the sheet is an ideal match for the dimensions of most cellars. It can be installed cross-wise, which accelerates the process by 50%. The self-sealing edge ensures that overlaps stay safely in place permanently. Because of its high compressive strength of c. 400kN/m², the sheet may be installed at depths of up to 10m. It is free from recycled material, bears the CE 0799-CPD-13 seal, and conforms to the requirements of EN 13252. The sheet is absolutely rot-proof and may be used as a reliable methane and radon gas drainage system

DELTA®-TERRAXX forms a continuous drainage layer. Its fused-on compression-resistant permanent-filtration geotextile reliably keeps the dimple structure from silting up. Forming a second water-impermeable envelope in front of the cellar wall waterproofing, the dimpled sheet affords all-round protection conforming to DIN 18533 in the event of any exposure to impounded, artesian, or seepage water.

It protects perimeter insulation boards from moisture, safeguards their insulation capability, and provides cellars with a special keep-warm-and-dry effect.

DELTA®-TERRAXX in der senkrechten Anwendungzoom
DELTA®-TERRAXX in der senkrechten Anwendungzoom

DELTA®-TERRAXX – the solution for Berlin pit lining

DELTA®-TERRAXX forms an outstanding filtration and seepage layer in Berlin pit lining applications. In this case, it is installed with the geotextile facing the lining. When concrete is being poured, the integrated sealing strip keeps cement paste from penetrating into and clogging up the seepage layer.

DELTA®-TERRAXX – the solution for Berlin pit liningzoom

Technical data: DELTA®-TERRAXX


A studded membrane made of special, high-density polyethylene and PP non-woven fabric.

Dimple height

approx. 9 mm

Compressive strength

approx. 400 kN/m2

On request also available with a compressive strength of 650 kN / m2 as DELTA®-TERRAXX TP

Air gap

approx. 7,9 l/m2

Servicetemperature range

- 30 °C to + 80 °C

Geocomposite for use in drain systems

D + F

Tensile strength

MD 14,2 bzw. CMD 14,3 kN/m (EN ISO 10319)

Dynamic perforation resistance

40 mm (EN 918)

Characteristic opening size

150 μm (EN ISO 12956)

Water permeability

8 · 10-2 m/s (EN ISO 11058)

Drainage capacity, water flow capacity in the plane

3,1 · 10-3 m2/s (EN ISO 12958) bei 20 kN/m2

Roll size

12,5 m x 2,4 m

Accessories for DELTA®-TERRAXX


    Ideally suited for mounting the DELTA-TERRAXX drain system on to perimeter insulating panels made of XPS with a thickness of 60mm or more. Usage: 1 piece/m².


    Edge terminating section for use with perimeter insulation. Patent pending.


    All-round fastener for all DELTA® dimpled and drainage sheets; for use on both sides.


  • DELTA®-TERRAXX flat roof (504 KB)

    DELTA®-TERRAXX flat roof
  • DELTA®-TERRAXX basement vertical(477 KB)

    DELTA®-TERRAXX basement vertical


Dörken GmbH & Co. KG

Dörken GmbH & Co. KG
Wetterstraße 58
D-58313 Herdecke

Tel          +49 23 30/63-0
Fax         +49 23 30/63-355

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